展开 (-5i+4j)(5cm,240)

解答

展开

(- 5 i + 4 j) (5 c m, 24 0^{\circ})

- 5 i (5 \cdot 24 0^{\circ}, m c) + 4 j (5 \cdot 24 0^{\circ}, m c)

求解步骤

(- 5 i + 4 j) (5 c m, 24 0^{\circ})

= (- 5 i + 4 j) (5 \cdot 24 0^{\circ}, m c)

使用分配律:

a (b + c) = ab + a c

a = (5 c m, 24 0^{\circ}), b = - 5 i, c = 4 j

= (5 c m, 24 0^{\circ}) (- 5 i) + (5 c m, 24 0^{\circ}) \cdot 4 j

使用加减运算法则

+ (- a) = - a

= - 5 i (5 \cdot 24 0^{\circ}, m c) + 4 j (5 \cdot 24 0^{\circ}, m c)

e x p an d (x + 1) (- \frac{1}{2} e^{- 2 x})

e x p an d (2 x + 3 y = 10) (- 2)

e x p an d cos ((3 x + 1) \frac{d}{d x} (3 x + 1))

e x p an d \frac{4 kj d - 2 kj l}{d ( d + l )}

e x p an d j (z - e^{- T j - T}) (z - e^{T j - T})